Optimizing The Calcium Supplement Method With The Solutes Clearance Law In Regional Citrate Anticoagulation

Background and objectivesContinuous renal replacement therapy(CRRT)is the most common renal replacement therapy in intensive care unit,and nowadays becoming the indispensable therapeutic option in rescuing critical patients.For the chronic maintenance dialysis strategy,the dialysis adequacy refers to achieve equilibrium between the metabolism rate and clearance rate of small and middle molecular weight toxins through intermittent hemodialysis.And having relative feasible evaluation indicators,such as urea reduction rate(URR)and single pool Kt/V(spKt/V).However,the population of acute dialysis are usually to be critical patients with unstable catabolism state and largely variable volume of distribution of urea.So,the chronic dialysis evaluation indicators are greatly limited in acute dialysis and now there is no clinical evaluation indicators about acute dialysis strategy.For this purpose,more and more scholars put forward effluent volume rate as the evaluation indicator of dialysis dose on the basis of adjusting for body weight.So,is that evaluation indicator feasible in clinical practice?Is there similar law of solutes clearance in different modality and different dose of CRRT?Based on the above assumptions,we plan to explore the solutes clearance law in different modality and different dose of CRRT in continuous renal replacement therapy,in order to make the evaluation of acute dialysis more accurate and more feasible.Whether chronic maintenance dialysis or acute dialysis,extracorporeal anticoagulation is the integral part of blood purification and is the key point to make CRRT smoothly and efficiently.Regional citrate anticoagulation(RCA)has effective extracorporeal anticoagulation,avoiding long time exposure to heparin when the patient in CRRT treatment.So,there is an urgent need to carry out RCA for those patients with active hemorrhage or high risk of bleeding.In addition to some potential metabolic complications,the most important factor of limiting the popularity of RCA in the clinical setting is the complicated operation and frequently monitoring the calcium level in the extracorporeal circulation tubes and in the body.Therefore,suitable calcium supplement is the key to make RCA success.For this reason,we plan to optimize the calcium supplement method with the solutes clearance law in regional citrate anticoagulation,in order to make RCA more safe and easier in the actual clinical practice.MethodsThis research is divided into two parts:Part Ⅰ Exploring the solutes clearance law in different modality and different dose of CRRT in continuous renal replacement therapy.Selected patients need CRRT treatment for a variety of reasons,adopting CVVHD and pre-CWH mode,substitution fluid flow or dialysis fluid flow on 1-5L/h,calculating the E/P ratio and dialysate side clearance rate of BUN,Cr,P and β2-MG.Part Ⅱ Optimizing the calcium supplement method with the solutes clearance law in regional citrate anticoagulation.Selected patients need CRRT treatment for a variety of reasons,adopting CVVHD and pre-CVVH mode,substitution fluid flow or dialysis fluid flow on 1-5L/h,citrate was infused at the arterial port at the rate of 4.5mmol/L Qpw,monitoring the calcium level in the extracorporeal circulation tubes and in the body,to maintain them in the target range.Calculating the E/P ratio of diffusible calcium,acquiring the linear regression equation of the diffusible calcium clearance and therapeutic dose in different modes and different dose.Acquiring the ratio of diffusible calcium and total calcium at the point of after the infusion of citrate and pre-filter,combining the citrate pharmacokinetics in the body,we plan to establish a simplified and quantitative calcium supplement equations on the basis of effluent volume rate.ResultsPart Ⅰ1.E/P ratio:Different molecular weight solutes’E/P ratio showed decreasing trend with the increasing of dialysate flow rate(P<0.05).Small molecular weight solutes such as BUN and Cr,have higher E/P ratio than middle and large molecular weight solutes such as β2-MG,at the same dialysate flow rate in CVVHD mode(P<0.001).Similar phenomenon was found in pre-CVVH mode.2.Clearance:Solutes’ clearance rate showed increasing trend with the increasing of dialysate flow rate,but with the decreasing of solutes’E/P ratio,the increasing range became smaller(P<0.001).Small molecular weight solutes such as BUN and Cr,have higher clearance rate than middle and large molecular weight solutes such as P2-MG,at the same dialysate flow rate in CVVHD mode(P<0.001).No matter what molecular weight it is,solutes’ clearance rate is always below the corresponding prescribed dosage(P<0.001).Similar phenomenon was found in pre-CVVH mode.Part Ⅱ1.Diffusible calcium has the similar clearance law with other solutes,that is diffusible calcium’clearance rate showed increasing trend with the increasing of dialysate flow rate(P<0.001).2.There is positive correlation between diffusible calcium’clearance rate and therapeutic dose in both CWHD and pre-CVVH mode(R2 is 0.90 and 0.68 respectively,P<0.001).We can predict the clearance rate on different therapeutic dose with the linear regression equation.3.The ratio of diffusible calcium and total calcium at the point of after the infusion of citrate and pre-filter is relatively fixed,different modes have different ratio.For CVVHD,the ratio is 0.92;for pre-CVVH mode,the ratio is 0.80.4.With the solutes clearance law,the amount of filter’ rem oval calcium per hour can be expressed as:fa × CcaT_art × Cl × 60 mmol.1000Conclusions1.There are different solutes removing mechanisms in different modality of CRRT.Solutes’ E/P ratio showed decreasing trend with the increasing of therapeutic dose.On the lower dose,effluent fliud rate can passably represent the actual dialysis dose,but with the increasing of therapeutic dose,prescribed dose can not match with the actual dialysis dose,actual dialysis dose is usually lower than the prescribed dose.2.Compared with the "Two-phase Calcium Supplementation Approach",our simplified and quantitative calcium supplement equations on the basis of effluent volume rate can quantize the amount of filter’s removal calcium.With regard to different modes and different therapeutic dose of CRRT,that equation would be more universal and make RCA more safe and easier in the actual clinical practice.